A new book by a former litigator at Kirkland & Ellis, one of the nation’s largest law firms, has delivered a frisson to the already rattled legal profession. In The Lawyer Bubble: A Profession in Crisis, Steven J. Harper argues that legal jobs are disappearing not because of short-term economic fluctuations but because of powerful long-term trends. The word bubble is an overstatement — it is hard to believe that the legal profession will end in the sort of high-speed implosion that subprime mortgages did. But the legal profession is facing some fundamental changes, and Harper deserves credit for sounding the alarm.

Harper begins his case with a basic and troubling set of facts: roughly 45,000 law students graduate each year with an average of more than $100,000 in debt — and only about half of them will find long-term, full-time jobs that require a legal degree. Even for graduates who get law jobs, he argues, the legal world is changing fast. Law firms that once prized professionalism and collegiality, he says, are increasingly operating like typical bean-counting businesses. And many law graduates are finding work only as “contract attorneys,” which often means doing document-review drudgery for low pay.

The decline in the market for lawyers is being driven by an array of forces. For some time now, but particularly since the economic downturn of 2008, corporate clients have been less willing to sign off on hefty legal bills. They have increasingly been balking at the top hourly rates of $1,000 that some partners charge — and at costly expenses, ranging from air travel to sushi dinners to copying charges.

And as a result of globalization, an increasing share of American legal work — particularly more by-the-numbers assignments, like document review — is being shipped overseas. Lawyers in India and other lower-wage markets are willing to do the work for a fraction of what American law firms would charge. Taking away even more of this work: newly sophisticated legal software that can do “document review” and other tasks for which lawyers were once needed.

The legal market is without question soft these days. Last June, the Association for Legal Career Professionals released a grim placement report stating that only 65.4% of law-school graduates had found jobs for which it was necessary to pass a state bar exam — down from 74.7% in 2008. And the Internet is full of first-hand accounts of law-school graduates who say that their law degree has not helped them get a law job — and, worse still, those who report that their degree has actually hurt their job prospects, since some employers now tell them they are overqualified for nonlegal positions.

Harper, who retired as a partner in 2008, argues that the profession’s leaders are a big part of the problem. He contends that big-firm managers are too focused on maximizing profits for the biggest, most rainmaking partners — at the expense of junior lawyers and the long-term interest of the firm. And he faults law-school deans for putting the interests and salaries of law professors ahead of the interests of their underemployed, debt-laden students.

Harper’s book has been warmly received in many parts of the mainstream media and the blogosphere, but the profession’s defenders have also been speaking out. Writing in the Wall Street Journalrecently, New York University law professor Richard Epstein accuses Harper of giving undue attention to a few big law firms that have gone belly-up in recent years — and ignoring that “the vast majority of big law firms have avoided this grisly fate.” And he takes umbrage at Harper’s broadsides at legal education, insisting that the sort of sophisticated and costly doctrinal training law schools provide is needed now more than ever.

It also helps that the number of new lawyers may finally be starting to decline. Applications to law schools are down sharply — plunging 38% just since 2010 — hitting a 30-year low. To keep the quality of students from falling, law schools have been cutting class sizes, and there are predictions that some of the weakest law schools may begin to shut down. Slowly, the supply of lawyers is likely to dwindle toward the demand for lawyers.

Harper’s big-picture argument is undoubtedly correct, and it is a real cause for concern. Bar associations and legal academics have begun talking about how the profession should adapt — discussions that are long overdue. The biggest problem with The Lawyer Bubble is not the warning it is sounding but its title; unlike tulips and other speculative bubbles in the past, lawyers will always be a necessity not a fad. But then, The Very, Very Challenging Job Market for Lawyers doesn’t have the same ring to it.